The present disclosure relates to additive manufacturing systems for printing three-dimensional (3D) parts and support structures. In particular, the present disclosure relates to materials for use in additive manufacturing systems, consumable assemblies retaining the materials, and methods of manufacturing and using the materials and assemblies in additive manufacturing systems to print articles.
Additive manufacturing systems are used to print or otherwise build printed parts from digital representations of the printed parts (e.g., AMF and STL format files) using one or more additive manufacturing techniques. Examples of commercially available additive manufacturing techniques include extrusion-based techniques, jetting, selective laser sintering, high speed sintering, powder/binder jetting, electron-beam melting, and stereolithographic processes. For each of these techniques, the digital representation of the printed part is initially sliced into multiple horizontal layers. For each sliced layer, a tool path is then generated, which provides instructions for the particular additive manufacturing system to print the given layer.
Additive manufacturing is generally a process in which a three-dimensional (3D) object is manufactured utilizing a computer model of the objects. The basic operation of an additive manufacturing system consists of slicing a three-dimensional computer model into thin cross sections, translating the result into two-dimensional position data, and feeding the data to control equipment which manufacture a three-dimensional structure in a layerwise manner using one or more additive manufacturing techniques. Additive manufacturing entails many different approaches to the method of fabrication, including fused deposition modeling, ink jetting, selective laser sintering, powder/binder jetting, electron-beam melting, electrophotographic imaging, and stereolithographic processes.
In a fused deposition modeling additive manufacturing system, a printed part may be printed from a digital representation of the printed part in a layer-by-layer manner by extruding a flowable part material along toolpaths. The part material is extruded through an extrusion tip carried by a print head of the system, and is deposited as a sequence of roads on a substrate in an x-y plane. The extruded part material fuses to previously deposited part material, and solidifies upon a drop in temperature. The position of the print head relative to the substrate is then incremented along a z-axis (perpendicular to the x-y plane), and the process is then repeated to form a printed part resembling the digital representation.
In fabricating printed parts by depositing layers of a part material, supporting layers or structures are typically built underneath overhanging portions or in cavities of printed parts under construction, which are not supported by the part material itself. A support structure may be built utilizing the same deposition techniques by which the part material is deposited. A host computer generates additional geometry acting as a support structure for the overhanging or free-space segments of the printed part being formed. Support material is then deposited from a second nozzle pursuant to the generated geometry during the printing process. The support material adheres to the part material during fabrication, and is removable from the completed printed part when the printing process is complete.
The 3D part may be fabricated on a polymeric sheet substrate releasably adhered to a build platen. The polymeric sheet substrate acts as a foundation or base on which to begin extrusion of material. The fabrication environment may be heated to delay solidification of the extruded part material. As is described in Comb et al., U.S. Pat. No. 5,939,008, vacuum pressure may be applied between the polymeric sheet substrate and the build platen to secure the sheet to the platen. However, heat-induced deformation of the sheet substrate (e.g., curling) caused by uneven heating of the sheet substrate, may prevent a vacuum from forming between the platen and the sheet, thus preventing secure retention of the sheet substrate on the build platen, until the sheet substrate flattens.